Cervical Cancer—Clinician FAQs
Why did the Canadian Task Force on Preventive Health Care (CTFPHC) develop new cervical cancer screening guidelines?
The previous CTFPHC guidelines on cervical cancer screening were developed in 1994. With the introduction of new tests, updated research, and a Human Papillomavirus (HPV) vaccine, cervical cancer screening has become an area of interest for many women and their health care providers.
Why is the CTFPHC increasing the age at which screening is recommended to 25?
The CTFPHC found no benefit for screening women under the age of 20 since the disease is extremely rare in this age group. However, young women are at an increased risk of high-grade abnormalities compared to older women, and are therefore more likely to experience unnecessary follow-up tests (e.g. colposcopy and biopsy). The vast majority of these “high-grade” abnormalities are caused by HPV infections that will regress due to active immune responses. As a result, the CTFPHC recommends not screening women under the age of 20.
For women 20–24 years of age, cervical cancer is rare and there is little, if any, reduction in mortality rates from screening. However, 10% of Pap tests in this group are abnormal, leading to further investigation and treatment. Therefore, the CTFPHC makes a weak recommendation not to screen women in this age cohort.
The prevalence of high-grade abnormalities steadily declines with age while cervical cancer incidence rises. Therefore, the proportion of abnormal Pap test results that may progress to cervical cancer is greater in women over the age of 25. The CTFPHC makes a weak recommendation for women 25–29 years of age and strong recommendation for women older than 30 years to screen for cervical cancer every 3 years.
Why does the CTFPHC recommend a screening schedule of every three years?
Screening every three years offers about 80% to 90% protection against cervical cancer. Screening more frequently (e.g. annually) offers little additional benefit and increases the risk of detecting high-grade abnormalities that will likely regress without any treatment, yet patients will undergo additional follow-up testing and experience greater potential harms. By establishing a screening schedule every 3 years, women balance the benefits of cervical cancer screening with the potential harms.
Some screening techniques for cervical cancer include HPV testing in combination with Pap tests. Why does the CTFPHC not include recommendations for this test?
Although the role of HPV in cervical cancer is well established, there is limited (though increasing) evidence available for HPV testing as a screening method. As a result, the CTFPHC has refrained from making a recommendation about HPV testing until more data are available. Given that this is a rapidly evolving field, the CTFPHC will revisit the cervical cancer recommendations in a few years as more research becomes available.
Will women forget to come in for their annual checkups if they do not need to attend for an annual Pap test?
Women will have their preventive health care needs best served if they attend for periodic health assessments at intervals that are based on the specific needs for their risk profile. The recommended interval should be discussed with each woman individually.
Many of my patients have been vaccinated against HPV. Why is the CTFPHC not providing different recommendations for these women?
Because the HPV vaccine was only recently introduced, there is currently insufficient evidence to support providing alternative screening recommendations for HPV-vaccinated women. The long-term effectiveness of the HPV vaccine in preventing cervical cancer will not be known for many years. Therefore, the CTFPHC currently recommends that HPV-vaccinated women commence regular Pap testing every 3 years from the age of 25.
Did cost effectiveness play any role in the development of the CTFPHC recommendations?
No, cost-effectiveness was not factored into the development of the CTFPHC recommendations.
The current recommendations were made specifically to:
- Bring Canadian practices in line with global best practices;
- Provide current and clear public health information to target audiences about cervical cancer screening; and
- Balance the demonstrated benefits of screening with its potential harms in women of different ages.
Why are provincial/territorial recommendations different than those found in the guideline?
The CTFPHC examined the latest available evidence for cervical cancer screening and has made recommendations to provide guidance for women and their health care providers around the optimal use and frequency of screening, based on that science.
Every province/territory has its own set of guidelines. Provincial guidelines are reviewed and updated periodically in all jurisdictions. Most provinces have been moving towards a later start age and longer screening interval in the past few years. It will be up to the individual provinces/territories to decide if and how the guideline changes their approach to screening. The CTFPHC guideline is there to help clarify the discussion on cervical cancer screening and assist in the decision making process.
Are there special recommendations for specific groups, such as Aboriginal women?
The CTFPHC searched for evidence to inform recommendations for screening Aboriginal women. They examined whether these women have a higher risk of invasive cervical cancer or a greater risk of harms (of screening), and if so, whether there was evidence that screening policies should be different for them. No evidence was found to support the need for differential screening in Aboriginal women (i.e., more or less frequent screening or different ages of starting/stopping).
The important issue is to ensure that screening is used by Aboriginal women and other groups who may have reduced access to health care, which may require creative and culturally sensitive strategies.
Who are the CTFPHC?
The CTFPHC is an independent panel of clinicians and methodologists that develop clinical practice guidelines for preventive health. Guidelines are based on a rigorous, systematic review of the most current available scientific evidence. These guidelines are aimed at primary care providers and other health care professionals, developers of preventive programs, policy-makers, and Canadian citizens.
How were the cervical cancer screening recommendations created?
The cervical cancer screening recommendations were developed by a working group composed of six CTFPHC members, two members of the Pan-Canadian Cervical Screening Initiative, and scientific staff from the Public Health Agency of Canada. They were based on a systematic review conducted by members of the McMaster University Evidence Review and Synthesis Center (ERSC), and a new Canadian epidemiological analysis conducted for the working group.
The working group engaged in a standard and rigorous process utilized by the CTFPHC for all guideline development i (Figure 1). The guidelines underwent internal and external peer review by experts in the field, and by stakeholders and partners.
Figure 1: CTFPHC Guideline Development Process
- Working Group establishes key research questions and analysis plan for systematic review.
- Systematic review is conducted by a team of methodologists and clinical experts at the ERSC using robust methods of literature searches and data synthesis.
- Working Group independently reviews the results of the systematic review with content experts,and develops recommendations by consensus. The Grading of Recommendation Assessment, Development and Evaluation (GRADE) system is used to assess the quality of evidence available and to rate the strength of the recommendations.
- Recommendations are revised and approved by the CTFPHC.
A complete description of recommendation development methods can be found in our Procedure Manual (.pdf, 1.4MB).